Sweetening hydrocarbon oils



Patented May 17, 1932 UNITED STATES PArl-:NTori-Ica ARTHUR R. MARTIN, OF DESTREI-IAN, LOUISIANA, AND PATRICK J'. KELLYv AND KENNETH H. REPATH, OF TAMPICO, MEXICO, 'ASSIGNORS T0 PAN AMERICAN PETROLEUM & TRANSPORT COMPANY, OF WILMINGTON, DELAWARE, AT CORPORVA- jj,

TION OF DELAWARE SWEETENING HYDROCARBON OILS v Application led April 25,

This invention relates to the sweetening of hydrocarbon oils and particularly petroleum distillate such as gasoline and kerosene.

The invention will be readily understood' from the-following description of a preferred method of .sweetening gasoline in accordance therewith.

The accompanying drawing illustrates diagrammatically a suitable apparatus for this purpose.` q

Referring to the drawing, is a line for supplying gasoline to be treated. The line 10 connects with the suction side of a pump 11, the pressure side of which is connected by pipe 12 to a .suitable mixer 13, shown by way of example as a chamber with numerous baiile plates 14. A pipe 15 connects with the pipe 12 for the purpose of supplying doctor (the usual sodium plumbite treating solution) thereto from the doctor receiving vessel 16. From the mixer 13 a pipe 17 leads to a settling chamber 18 which is of such size that .substantially all the sodium plumbite sludge settles out of the gasoline therein, together with more or less lead sulfide produced by the interaction of sulfur compounds of the gasoline with the doctor. The chamber 18 is preferably provided with a gauge glass 19. From the base of the settling chamber 18 a valved pipe 2O leads to the vessel 21. From the top o-f the chamber 18, a pipe 22 leadsto a mixer V23 which may be similar to the mixer 13. The pipe 22 is provided with means for supplying sulfur in reactive form thereto, for example, a pipe 24 may be providedv which communicates with pipe 22, for the purpose of supplying gasoline saturated with sulfur in the quantity necessary to decompose the lead compounds retained by the plumbite treated gasoline. From the mixer 23 a pipe 25 leads to a settling chamber 26 which is of such size that substantially all the lead sulfide which is carried over by the gasoline from settling chamber 18 and which is produced by the reaction of the sulfur introduced by pipe 24 upon the leadcompounds retained by the plumbite treated gasoline, is precipitated therein. From the top of chamber 26 a pipe 27 leads the treated gasoline to storage. From the bottom of the chamber 26 a pipe 28 1927. Serial No. 186,276:

leads to a reaction vessel 29, a pump 30 being provided in the pipe 28. Pipes 31, 32, and 33 are adapted to supply sulfuric acid, water and sodium hydroxide solution to the Vvessel 29. The vessel 29 is provided near its base 'f with a valved liquid drawoff pipe 34 and at its base with a pipe 35 which leads to the doctorreceiving vessel 16. The vessel 16 is preferably at a lowery level than vessel 29.

so that liquid may flow from the latter to the former vessel through pipe 35 by gravity. In the lower portion of vessel 29 are located perforated coils or pipes 36 and connected with pipes 38 and 39 respectively for supplying air and steam into the liquid in the vessel 29. From the vessel 21 a valved pipe 40 leads to the vessel 29. vThe vessel 21 is preferably at a higher level than the vessel 29, so that liquid may ow from theformer to the latter by gravity. From the base of vessel 16 a pipe 41 leads to a pump 42, the outlet of which is connected with the pipe 15. A pipe 43 connects with the pipe for the purpose of supplying fresh doctor thereto.

The opera-tion is as follows. Gasoline to be sweetened is supplied by pipe 10 to the pump 11 which forces it through pipe 12. Doctor is drawn from vessel 16 and supplied by pump 42 through pipe 15to pipe ,12,

line which constitutes the upper layer in settling chamber 18, together with vsome lead sulfidesuspended therein passes through pipe 22 and gasoline containing sulfur in solution is supplied by pipe 24 in such quantity that the sulfur Vcontent will react with 'the lead compounds in the gasoline to yield sweet gasoline. The gasoline from pipes'.V 22 and 24 f is thoroughly mixed rin mixer 23 and the mixture then passes to the settlingchamber 26, lead sulfide precipitates in the chamber 26,

and the treated gasoline passes by pipe 27 to storage.

When a quantity of lead sulfide has accumulated in chamber 26, it is pumped through pipe 28 to the reaction vessel V29. Concentrated sulfuric acid, suitably 98% acid, is supplied by pipe 31 and the mixture agitated vby introducingair by pipe 38 .and perforated Y 'coil 36. lAgitationi may be` effected in any othersuitablefmanneryif desired. YThe lead sulfide is thereby converted into lead sulfate as follows:

4The reaction is ordinarily completed` in about two hours. The sulfateis then allowed to settle and excess acid isfdrawn off by pipe 34. Water is now. suppliedto the vessel. 29 by. pipe `32. andthe sulfate isgwashed withthe rzorwater Whilev agitating by air from the pipe 38.-YV The sulfate isallowed to settle andthe Water drawn offby pipe 342 This operation may be repeated iff necessary until the sulfate retains` only a small amount of'acid.

The spentdoctor, rich in sodium hydroxide and low. in lead, which settlesout in chamber 18 may be withdrawn intermittently orcontinuously tothe vesselJ 2l. From the vesselV 2l' this liquidV is led by piped() to the reaction vessel29where it isfmixe'd with the Washed leadesulfate, the productionot` which has been hereinbefore described.` rllhe'mixture isragitatedwith air and-steam.introducedbypipes 38 andf39, for about. one hour, until, the solution is saturated with lead; The reactionimay be expressed as follows :k

Pbso.+-3Naoir= Puoi-n'onmnazsorigo.

sulfate in the partially exhausted doctor solution thereby converting it into active plumbite.

2. The method of sweetening hydrocarbon oils with doctor and producing doctor from the partially exhausted doctor resulting from such sweetening operation which consists in treating-said oilfwith doctor, separatingrpartially exhausted' doctor therefrom, subsequent-ly adding sulfurto saidoil and separating lead sulfide therefrom, converting said sulfide into sulfate, and dissolving said sulfate in caustic soda to produce doctor.

3. The method of vsweetening hydrocarbon oil distillate 'which consists in treating said oil distillate with doctor., separa-ting spent doctor of reduced leadand increased, alkali content therefrom,` subsequentlyv precipitating anhydrous lead sulfide from said distillate, treating said sulfide-with sulfuricy acid to vconvert it into lead sulfate, dissolving said sulfate in said spent doctor to replenish the lead content thereof,y andreutilizing thejdoctor for the sweeteningof distillate. v

4. The method of sweeteninghydrocarbon oils, which consistsintreating said oil with doctor.. separating partially exhausted docvtor, together with lead sulfide,Y therefrom,

subsequently precipitating substantially anhydrous lead sulfidefrom the oil, converting said substantially 'anhydrous lead sulfide into lead sulfate, dissolving said sulfate in said partially exhausted doctor'solution7 thereby converting it into active plumbit'e,

and reusing the resulting doctor solution con- 1 taining leadV sulfide in the sweetening of hydrocarbon oils. f

5. The method of sweetening hydrocarbon oils, which consists in treating said oil with doctor, separating partially exhausted doctor, together with lead sulfide, therefrom, subsequently adding sulfur to said oil and separating lead sulfide therefrom, converting'las-t said sulfide into sulfate, dissolvingsaid sulfate in the partially exhausted doctor- -solution, thereby converting' it into yactive plumbite, and re-using the resulting doctor solution containing lead sulfide in the sweeteningof hydrocarbon oils. ARTHUR JR.k MARTI-N.

PATRICK J'. KELLY. KENNETH' H, REPATH.'l

not limited thereto except` by the terms-ofthe Y appendedfclaims.Y

We. claim..`

Vl. The methodof sweetening hydrocarbon oils with. doctor and reactivating the. partially exhausted. doctor resulting from such sweetening operation Whichconsists in treatingsaid oilwith doctor,.separating partially exhausted doctor therefrom,` subsequently precipitating substantially anhydrous lead sulde fromthe roil, converting said lead A85 sulfidev into lead sulfate and dissolving said 

